Different antioxidant effects of polyphenols on lipid peroxidation and hydroxyl radicals in the NADPH-, Fe-ascorbate- and Fe-microsomal systems |
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Authors: | Ozgová Sárka Hermánek Josef Gut Ivan |
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Institution: | National Institute of Public Health, Centre of Occupational Diseases, Srobárova 48, 100 42 Praha 10, Czech Republic. |
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Abstract: | Antioxidant and pro-oxidant effects of 14 naturally occurring polyphenols (PP) on rat liver microsomal lipid peroxidation (LP) and hydroxyl radical (*OH) production were studied in NADPH-dependent, 50 microM Fe(2+)-500 microM ascorbate (Fe-AA) or 50 microM Fe(2+) system, respectively. LP determined by the thiobarbituric acid method was inhibited in the NADPH system by flavonols and trans-resveratrol that were more effective than other flavonoids and derivatives of benzoic and cinnamic acid and were mostly more efficient than in the Fe-AA system. Inhibition of LP in the Fe system was higher by one order of magnitude than in the Fe-AA system. *OH production in the NADPH system, measured by formaldehyde production, was decreased by myricetin, fisetin and quercetin, but increased by kaempferol, morin and trans-resveratrol, indicating that z.rad;OH played a minor role in LP, which all of these PP inhibited. None of these PP at up to 40 microM concentration quenched *OH in the Fe-AA system. All tested PP, except trans-resveratrol and gentisic acid, spectrally interacted with Fe(2+) or Fe(3+), indicating formation of complexes or oxidation of PP. In contrast to the NADPH system we found no correlation between Fe(2+) chelation and inhibition of Fe-AA- or Fe-dependent LP indicating that iron chelation did not play a significant role in the two latter systems. It is concluded that the inhibition of LP by PP was apparently due to their hydrogen donating properties rather than chelation of iron. |
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Keywords: | els-cdn OH" target="_blank">com/sd/entities/rad" class="glyphImg">OH hydroxyl radical AA ascorbic acid CYP cytochrome P-450 Ep/2 half peak oxidation potential LP lipid peroxidation MDA malondialdehyde O2? superoxide anion radical PP polyphenols ROels-cdn " target="_blank">com/sd/entities/rad" class="glyphImg"> alkoxyl radical ROOels-cdn " target="_blank">com/sd/entities/rad" class="glyphImg"> peroxyl radical TBARS thiobarbituric acid-reactive substances |
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